Double hammer for hammer mills



Sept. 11, 1945. `.1. G. BRYANT, .IRVIA l' 2,384,531

DOUBLE HAMMER FOR HAMMER MILLS Filedl June 26. 1944 Patented Sept. ll, 1945 UNITED STATES ATENT OFFICE 2,384,531 DOUBLE HAMMER FOR HAMMER MrLLs James G. Bryant, Jr., Port Huron, Mich.

Application June 26, 1944, Serial No. 542,034

2 Claims.

sive amount Of abrasive present in grain, and even without abrasive materials, the impossibility of lubricating the hammer mounting, has resulted in very rapid wear of the pins and hammers, requiring constant replacement, with the necessity for shut-downs and arduous work in the opening of the mill casing, and the removal and replacement of the worn parts. Construction of the mills has been greatly simplied with a View to economy in the hammer elements and their mountings, the present practice involving the use of hammers of fiat metal stock, apertured and set upon cross pins with suitable spacers, the pins being set through a number of discs of large diameter mounted upon a rotary shaft, the shaft and discs comprising the rotor of the mill. These flat plate hammers rapidly cut into the cross pins upon which they are pivotally swung, and the openings in the hammers through which the pins are inserted wear to an eccentric form, so that before a satisfactory amount of service can be obtained from a hammer, which still has a substantial amount of material in the principal working parts, it must be replaced on account of eX- cessive wear of the eye-portion or aperture through the hammer, by which it is suspended from the cross pin. Also, notwithstanding the fact that specially hardened steel of hard alloy stock is used in the cross pins, these become quickly cut and deeply grooved by the hammers, requiring great watchfulness in order to avoid the possibility that unforeseen conditions may result in more rapid wear than usual, with consequent breakage Of a pin and serious injury to the mill by release of the hammers.

It is a further important aim of the invention to enable provision of a double hammer witha novel'mounting, while still retaining advantages of alternate wide and narrow spacing of the hammers, or the hammers on successive pins may be arranged out of line with each otherthat is, not in a common planeand it is an important aim of my invention to present a double hammer in which the advantage of this offset practice may be continued.

As is well known, the trade has found that most effective Work can be done with hammers of very thin plate stock, both on account of the fact that they work better upon the stock being ground, but also require less power for operation of the mill. But these narrow hammers cause wear of the cross pins greatly out of proportion to the relative thickness of the blades. By using hammers a quarter of an'inch thick, it has been found that very little wear even on a. soft steel pin is produced, but the best practice involves the use of sheet steel stock less than one-tenth of an inch thick, some mills using hammers which are slightly more than One-sixteenth of an inch thick. Itis an important advantage of my invention that the very thinnest material may be used, yet the mill may be operated for long periods without appreciable wear on the cross pins. Y

A further important aim of the invention is to enable provision of a wide bearing support for hammersl in such mills, yet avoiding objectionable weight in the material used and'minimizing the number of parts required, aswell as assemblyoperations in assembling the rotor and hammers, as well as in the renewals and replacements. By the manner of constructing my hammers, it is made possible to eliminate one-half ofthe number oi spacers heretofore required, and more than one-half the Weight of such spacers.

`A further important aim of the invention is to present a novel bearing element `for hammers of this kind, and a novel assembly relation to the bearing element and new hammer.

Additional objects, advantages and features of invention reside in the construction, arrangement and combination of parts involved in the embodiment of the invention, as will be more readily understood from the following description and accompanying drawing, wherein Figure 1 is a formal cross sectional view of a mill embodying my invention, complete details of Crusher and conveyor devices, as well as particulars of case construction being omitted, these not being essential to an understanding of my Figure y2.

invention, which resides in the specic construction of the hammers and their mounting; l'

Figure 2 is a view of a portion of one of the cross bars of the mill, with two of my hammers mounted thereon. Figure 3 is a section on the line 3 3 of Figure 2. v

Figure4 is a section across the pin, on the line `d-fl of Figure 2.

Figure 5 is a similar view on the line 5-5 of Figure 6 is a detail elevation of one of the saddle bearings for my hammers.

Figure '1 is a side elevation of the saddle bearing.

Figure 8 is a cross section showing the hammer unit set t the left instead of to the right.

Referring more particularly to the drawing, there is illustrated conventionally a hammer mill comprising a rotor lll, of conventional construction mounted revolubly in a case 'I2 of suitable form, the mill including a feeding hopper I3 in which a crusher feeder device may be included, indicated in part at I4, the mill including also a screen I5 of suitable structure, `anda discharge conveyor I 6 of any usual form. The rotor, as is usual, comprises a multiplicity of 'large steel plate discs of substantial thick-ness, indicated at I1, these discs being secured rigidly and permanently upon a drive shaft I8, conventionally mounted and driven. A series of cross pins 20 are set removably through the discs in a concentric .series spaced a .short distance .inwardly of the peripheries of the discs, a usual .diameter iorsuch disc 'being .2B inches, and the circle on which the pinsare centered -would properly be 23 inches .in diameter vin such case. 'Ihe pins in such .a -mill :may .be .of five-eighths inch steel. .In the case of my mill, this steel .need not be vof as .expensive `an .alloy as is required with the -ordinary thin hammersand lmay be hardened in any inexpensive way suitable for the material, or .may he relatively soft, since by ,my .method of mounting, )there is but little Wearmanifest. -Such mills .are made .in various widths, the discs -being .spaced apart in such a mill as illustrated approximately `one and ve-.sixteenths inches, .and mydouble hammerismadein a widthcoordinated `with this .spacing in aspecic way to enable .the

.effective staggering of. the hannners :on successive .pins.

Upon .each of the pins 20, between each two mutually adjacent discs, a double hammer 2l .is provided, which is formed .of a strap of hardened steel plate `bent midway of .its length .so that .its -opposite end portions vare .brought into `.parallel relation, the .bend constituting a semi-circular bight 22, the ,twohammer arms 23 thus .formed being spaced apart comewhat more than half the .space between two of the discs, so tha-t'the extreme .faces of the hammers ,are .spaced apart fh Pof an inch, or a little A.more than two-thirds the width ofthe .space between vtwo discs. The two hammer `arms `are `centrally .apertured at 24, immediately .adjacent the bight portion, these .apertures being circular and of .a Ydiameter somewhat greater than `that of the cross pin, -so that the hammer -may -be hung from the .pin with a clearance entirely around :the pin between the edges ofthe ,opening-and the pin, these openings being immediatelyradacent the base .of the semicircular bight 22 `in a mill of the character `and size indicated herein. The hammer arms Ymay have a-length of ,approximately six and one-half inches to the .centers Iof the open-ings 24 and a customary width in :such hammers is one and three quarters inches. -On account of the improved vwear characteristics of my Yhammer and mounting, I have found that it is advantageous to 'use sheet 4steel stock of approximately .onesixteenth inch thickness for the hammer, this shaving a further advantage in enabling more rapid, effective and economical "hardening of the hammer. The space between the hammers and the bight and around the openings 24 is thus -approximately slightly more than three-quarters of an inch. Set snugly in the bight of each hammer, there is a piece of steel stock having a diameter of approximately three-quarters of an inch, and having in one side a semi-circular saddle bearing recess of such radius as to t, snugly around the cross rod 20. The rod pieces 25 may be termed saddle blocks in view of the nature of the bearing which they afford upon the cross rod in use. The saddle blocks are simply set loosely in the bight of the hammer units and are securely retained therein when the rod is inserted through the apertures 24 while the sad- `dle bearing 24 is aligned to receive the cross rod `tl'ieretlnough. vOne hammer unit is mounted between each two discs, as before mentioned, and at one side of each hammer unit a spacer washer or collar 21 4is disposed loosely around the cross pin, so as to hold the hammer unit close to one .of the discs I1, and spaced from the other `by the collar 21. On one pin the hammer units Aare 4usually disposed closely adjacent the respective discs in one direction, and on the next pin are disposed closely adjacent the discs in `the opposite direction, `and by this means hammers of adjacent pins are thrown out of line so that they may more effectively engage feed stock .and the like being ground, .and for other reasons. Eachpin `adj acent one end is formed with a transverse bore 28 and one of the collars 2] is likewise -apertured to aline with the bore rthrough the pin, a cotter pin 29 being engaged commonly through the -collal` and cross pin, as :in .Figure vEl, so as to hold the cross pin against possibility of displacement longitudinally.

In the assembly of .the device, a hammer unit with .one of the saddle blocks .25 set in its .bight portion and the recess 2K6 of the hammer unit 2l .approximately aligned with the apertures 24; .and .after the pin is suitably started through a -disc I1., the hammer unit is held .suspended with Aits hammer arms extended vertically upward and the .apertures 24 of .the saddle .bearing 25 aligned -with the pin, while the latter is moved longitudinally through the hammer unit. A Ycollar 21 may he vengaged upon the pin before vor after insertion of .the .pin through the hammw unit. This voperation is repeated between each two discs as .the .pin is inserted1 until the hammer units .are .mounted .between each .two mutually ladjacent discs, .after which, .the proper collar with apertures beingr .disposed around the pin adjacent one end, .the .cotterpin 19 -is inserted therethrough. Removal of the .hammer units may be effected -by .a reverse procedure, as may be readily appreciated.

The depth of the .saddle bearing recess 2B in .thesaddle Ablock 25 is such .that when initially emplaced, the cross pin will be located nearer that side .of the aperture 24 which is nearest the extremities of the .hammer arms, and therefore, under centrifugal force, as the weight of the ,hammers is thrown radially outward, the saddle bearing comes to rest upon the cross pin with the edges of the openings .24 spaced well away from the cross pin, so that even under considerable vibration, .there is no possibility of abrasion of the cross pin by .the hammer, and .the load of the Yhammer .unit is .sustained upon a .broad surface in `the saddle bearingvrecess .extended some distance longitudinally and circumferentially upon ythe `cross pin.

The .saddle blocks are cut diagonally at each end, their end surfaces sloping longitudinally of the block away from ,adjacent the sides 'of the bearing recess 25, and when the device is 'assembled as described, the longer part of the saddle block is extended through the bight of the harn mer, so that the bight portion of the hammer is supported throughout the width of the ,hame mer unit, and liability of springing or sagging and distortion of the hammer is thus safeguarded against.

While I have disclosed my invention with great particularity, as to the specific form and proportions of elements, it will, nevertheless, be understood that this is exemplary, and that various modications in the size, proportions and materials of parts may be made Without departing from the spirit of the invention, including substitution of equivalents and differences in combinations, all as may be included within the scope of the following claims, wherein I claim:

1. A hammer unit for hammer mills comprising a metal strip bent into U shape, forming a bight and providing a pair of hammer arms, said arms having transversely aligned apertures adjacent the bight and spaced therefrom, a saddle block fitted in the bight and having a semicircular recess aligned with said apertures to receive a cross pin commonly therethrough.

2. A hammer unit for hammer mills comprising a metal strip bent into U shape, forming a bight and providing a pair of hammer arms, said arms having transversely aligned apertures adjacent the bight and spaced therefrom, a saddle block tted in the bight and having a semicircular recess aligned With said apertures to receive a cross pin commonly therethrough, the bearing portion of said recess being of such dimansions as to space the cross pin from contact with the aligned apertures.

JAMES G. BRYANT, JR. 

